Inbred maize line PHAG6

ABSTRACT

An inbred maize line, designated PHAG6, the plants and seeds of inbred maize line PHAG6, methods for producing a maize plant produced by crossing the inbred line PHAG6 with itself or with another maize plant, and hybrid maize seeds and plants produced by crossing the inbred line PHAG6 with another maize line or plant.

FIELD OF THE INVENTION

This invention is in the field of maize breeding, specifically relating to an inbred maize line designated PHAG6.

BACKGROUND OF THE INVENTION

The goal of plant breeding is to combine in a single variety or hybrid various desirable traits. For field crops, these traits may include resistance to diseases and insects, tolerance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, and plant and ear height, is important.

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.

Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two different homozygous lines produces a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform.

Maize plants (zea mays L.), often referred to as corn in the United States, can be bred by both self-pollination and cross-pollination techniques. Maize has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in maize when wind blows pollen from the tassels to the silks that protrude from the tops of the ears.

A reliable method of controlling male fertility in plants offers the opportunity for improved plant breeding. This is especially true for development of maize hybrids, that relies upon some sort of male sterility system. There are several options for controlling male fertility available to breeders, such as: manual or mechanical emasculation (or detasseling), cytoplasmic male sterility, genetic male sterility, gametocides and the like.

Hybrid maize seed is typically produced by a male sterility system incorporating manual or mechanical detasseling. Alternate strips of two inbred varieties of maize are planted in a field, and the pollen-bearing tassels are removed from one of the inbreds (female). Providing that there is sufficient isolation from sources of foreign maize pollen, the ears of the detasseled inbred will be fertilized only from the other inbred (male), and the resulting seed is therefore hybrid and will form hybrid plants.

The laborious, and occasionally unreliable, detasseling process can be avoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMS inbred are male sterile as a result of factors resulting from the cytoplasmic, as opposed to the nuclear, genome. Thus, this characteristic is inherited exclusively through the female parent in maize plants, since only the female provides cytoplasm to the fertilized seed. CMS plants are fertilized with pollen from another inbred that is not male-sterile. Pollen from the second inbred may or may not contribute genes that make the hybrid plants male-fertile. Usually seed from detasseled fertile maize and CMS produced seed of the same hybrid s are blended to insure that adequate pollen loads are available for fertilization when the hybrid plants are grown.

There are several methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. These and all patents referred to are incorporated herein by reference. In addition to these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. patent application No. 07/848,433, have developed a system of nuclear male sterility that includes: identifying a gene that is critical to male fertility; silencing this native gene that is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not "on" resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning "on" the promoter, that in turn allows the gene that confers male fertility to be transcribed.

There are many other methods of conferring genetic male sterility in the art, each with it's own benefits and drawbacks. These methods use a variety of approaches such as delivering into the plant a gene encoding a cytotoxic substance associated with a male tissue specific promoter or an antisense system in which a gene critical to fertility is identified and an antisense to that gene is inserted in the plant (see: Fabinjanski, et al. EPO No. 89/3010153.8 publication No. 329,308 and PCT application No. PCT/CA90/00037 published as WO 90/08828).

Another system useful in controlling male sterility makes use of gametocides. Gametocides are not a genetic system, but rather a topical application of chemicals. These chemicals affect cells that are critical to male fertility. The application of these chemicals affects fertility in the plants only for the growing season in which the gametocide is applied (see Carlson, Glenn R., U.S. Pat. No.: 4,936,904). Application of the gametocide, timing of the application and genotype specificity often limit the usefulness of the approach.

The use of male sterile inbreds is but one factor in the development of maize hybrids. The development of maize hybrids requires, in general, the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop inbred lines from breeding populations. Breeding programs combine the genetic backgrounds from two or more inbred lines or various other broad-based sources into breeding pools from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which of those have commercial potential.

Pedigree breeding starts with the crossing of two genotypes, each of that may have one or more desirable characteristics that is lacking in the other or that complement the other. If the two original parents do not provide all the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive generations. In the succeeding generations the heterozygous condition gives way to homogeneous lines as a result of self-pollination and selection. Typically in the pedigree method of breeding five or more generations of selfing and selection is practiced: F₁ >F₂ ; F₃ >F₄ ; F₄ >F₅, etc.

Recurrent selection breeding, backcrossing for example, can be used to improve an inbred line. Backcrossing can be used to transfer a specific desirable trait from one inbred or source to an inbred that lacks that trait. This can be accomplished, for example, by first crossing a superior inbred (recurrent parent) to a donor inbred (non-recurrent parent), that carries the appropriate gene(s) for the trait in question. The progeny of this cross is then mated back to the superior recurrent parent followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent. After five or more backcross generations with selection for the desired trait, the progeny will be heterozygous for loci controlling the characteristic being transferred, but will be like the superior parent for most or almost all other genes. The last backcross generation would be selfed to give pure breeding progeny for the gene(s) being transferred.

A single cross hybrid maize variety is the cross of two inbred lines, each of that has a genotype that complements the genotype of the other. The hybrid progeny of the first generation is designated F₁. In the development of hybrids only the F₁ hybrid plants are sought. Preferred F₁ hybrids are more vigorous than their inbred parents. This hybrid vigor, or heterosis, can be manifested in many polygenic traits, including increased vegetative growth and increased yield.

The development of a hybrid maize variety involves three steps: (1) the selection of plants from various germplasm pools for initial breeding crosses; (2) the selfing of the selected plants from the breeding crosses for several generations to produce a series of inbred lines, that, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with different inbred lines to produce the hybrid progeny (F₁). During the inbreeding process in maize, the vigor of the lines decreases. Vigor is restored when two different inbred lines are crossed to produce the hybrid progeny (F₁). An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between any two inbreds will always be the same. Once the inbreds that give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.

A single cross hybrid is produced when two inbred lines are crossed to produce the F₁ progeny. A double cross hybrid is produced from four inbred lines crossed in pairs (A×B and C×D) and then the two F₁ hybrids are crossed again (A×B)×(C×D). Much of the hybrid vigor exhibited by F₁ hybrids is lost in the next generation (F₂). Consequently, seed from hybrid varieties is not used for planting stock.

Maize is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop high-yielding maize hybrids that are agronomically sound based on stable inbred lines. The reasons for this goal are obvious: to maximize the amount of grain produced with the inputs used and minimize susceptibility of the crop to environmental stresses. To accomplish this goal, the maize breeder must select and develop superior inbred parental lines for producing hybrids. This requires identification and selection of genetically unique individuals that occur in a segregating population. The segregating population is the result of a combination of crossover events plus the independent assortment of specific combinations of alleles at many gene loci that results in specific genotypes. Based on the number of segregating genes, the frequency of occurrence of an individual with a specific genotypes. Based on the number of segregating genes, the frequency of occurrence of an individual with a specific genotype is less than 1 in 10,000. Thus, even if the entire genotype of the parents has been characterized and the desired genotype is known, only a few if any individuals having the desired genotype may be found in a large F₂ or S₀ population. Typically, however, the genotype of neither the parents nor the desired genotype is known in any detail.

In addition to the preceding problem, it is not known how the genotype will react with the environment. This genotype by environment interaction is an important, yet unpredictable, factor in plant breeding. A breeder of ordinary skill in the art cannot predict the genotype, how that genotype will interact with various environments or the resulting phenotypes of the developing lines, except perhaps in a very broad and general fashion. A breeder of ordinary skill in the art would also be unable to recreate the same line twice from the very same original parents as the breeder is unable to direct how the genomes combine or how they will interact with the environmental conditions. This unpredictability results in the expenditure of large amounts of research resources in the development of a superior new maize inbred line.

Pioneer research station staff propose about 400 to 500 new inbreds each year from over 2,000,000 pollinations. Of those proposed new inbreds, less than 50 and more commonly less than 30 are actually selected for commercial use.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred maize line, designated PHAG6. This invention thus relates to the seeds of inbred maize line PHAG6, to the plants of inbred maize line PHAG6, and to methods for producing a maize plant produced by crossing the inbred line PHAG6 with itself or another maize line. This invention further relates to hybrid maize seeds and plants produced by crossing the inbred line PHAG6 with another maize line.

Definitions

In the description and examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided. NOTE: ABS is in absolute terms and %MN is percent of the mean for the experiments in which the inbred or hybrid was grown. These designators will follow the descriptors to denote how the values are to be interpreted. Below are the descriptors used in the data tables included herein.

ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9 visual rating indicating the resistance to Anthracnose Stalk Rot. A higher score indicates a higher resistance.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were not barren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.

BU ACR=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushels per acre adjusted to 15.5% moisture.

CLN=CORN LETHAL NECROSIS (synergistic interaction of maize chlorotic mottle virus (MCMV) in combination with either maize dwarf mosaic virus (MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV)). A 1 to 9 visual rating indicating the resistance to Corn Lethal Necrosis. A higher score indicates a higher resistance.

COM RST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicating the resistance to Common Rust. A higher score indicates a higher resistance.

D/D=DRYDOWN. This represents the relative rate at which a hybrid will reach acceptable harvest moisture compared to other hybrids on a 1-9 rating scale. A high score indicates a hybrid that dries relatively fast while a low score indicates a hybrid that dries slowly.

DIP ERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodia macrospora). A 1 to 9 visual rating indicating the resistance to Diplodia Ear Mold. A higher score indicates a higher resistance.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.

D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for drought tolerance, and is based on data obtained under stress conditions. A high score indicates good drought tolerance and a low score indicates poor drought tolerance.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in inches.

EAR MLD=General Ear Mold. Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining the specific mold organism, and may not be predictive for a specific ear mold.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.

ECB 1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinia nubilalis). A 1 to 9 visual rating indicating the resistance to preflowering leaf feeding by first generation European Corn Borer. A higher score indicates a higher resistance.

ECB 2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING (Ostrinia nubilalis). Average inches of tunneling per plant in the stalk.

ECB 2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1 to 9 visual rating indicating post flowering degree of stalk breakage and other evidence of feeding by European Corn Borer, Second Generation. A higher score indicates a higher resistance.

ECB DPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Dropped ears due to European Corn Borer. Percentage of plants that did not drop ears under second generation corn borer infestation.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on per plot basis for the inbred or hybrid.

EYE SPT=Eye Spot (Kabatiella zeae or Aureobasidiurn zeae). A 1 to 9 visual rating indicating the resistance to Eye Spot. A higher score indicates a higher resistance.

FUS ERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusarium subglutinans). A 1 to 9 visual rating indicating the resistance to Fusarium ear rot. A higher score indicates a higher resistance.

GDU=Growing Degree Units. Using the Barger Heat Unit Theory, that assumes that maize growth occurs in the temperature range 50° F.-86° F. and that temperatures outside this range slow down growth; the maximum daily heat unit accumulation is 36 and the minimum daily heat unit accumulation is 0. The seasonal accumulation of GDU is a major factor in determining maturity zones.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimum temperature used is 50° F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.

GIB ERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberella zeae). A 1 to 9 visual rating indicating the resistance to Gibberella Ear Rot. A higher score is indicates a higher resistance.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual rating indicating the resistance to Gray Leaf Spot. A higher score indicates a higher resistance.

GOS WLT=Goss' Wilt (Corynebacteriurn nebraskense). A 1 to 9 visual rating indicating the resistance to Goss' Wilt. A higher score indicates a higher resistance.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.

H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plant densities on 1-9 relative rating system with a higher number indicating the hybrid responds well to high plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to increased plant density.

HC BLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporium carbonum). A 1 to 9 visual rating indicating the resistance to Helminthosporium infection. A higher score indicates a higher resistance.

HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates the percentage of plants not infected.

INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acre assuming drying costs of two cents per point above 15.5 percent harvest moisture and current market price per bushel.

INCOME/ACRE. Income advantage of hybrid to be patented over other hybrid on per acre basis.

INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1 over variety #2.

L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plant densities on a 1-9 relative system with a higher number indicating the hybrid responds well to low plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to low plant density.

MDM CPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus and MCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating the resistance to Maize Dwarf Mosaic Complex. A higher score indicates a higher resistance.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.

MST ADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 over variety #2 as calculated by: MOISTURE of variety #2-MOISTURE of variety #1=MOISTURE ADVANTAGE of variety #1.

NLF BLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilum turcicum). A 1 to 9 visual rating indicating the resistance to Northern Leaf Blight. A higher score indicates a higher resistance.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in inches.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.

It should be understood that the inbred can, through routine manipulation of cytoplasmic or other factors, be produced in a male-sterile form.

POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.

POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage of variety #1 over variety #2 as calculated by PLANT POPULATION of variety #2-PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety #1.

PRM=PREDICTED Relative Maturity. This trait, predicted relative maturity, is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is referred to as the Comparative Relative Maturity Rating System that is similar to the Minnesota Relative Maturity Rating System.

PRM SHD=A relative measure of the growing degree units (GDU) required to reach 50% pollen shed. Relative values are predicted values from the linear regression of observed GDU's on relative maturity of commercial checks.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30° angle or greater would be counted as root lodged.

RTL ADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1 over variety #2.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A maize breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.

SLF BLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipolaris maydis). A 1 to 9 visual rating indicating the resistance to Southern Leaf Blight. A higher score indicates a higher resistance.

SOU RST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual rating indicating the resistance to Southern Rust. A higher score indicates a higher resistance.

STA GRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.

STD ADV=STALK STANDING ADVANTAGE. The advantage of variety #1 over variety #2 for the trait STK CNT.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.

STK LDG=STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.

STW WLT=Stewart's Wilt (Erwinia stewartisi). A 1 to 9 visual rating indicating the resistance to Stewart's Wilt. A higher score indicates a higher resistance.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at the time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data is given as a percentage of tillers: number of tillers per plot divided by number of plants per plot.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel) adjusted for 15.5 percent moisture.

TSW ADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1 over variety #2.

WIN M%=PERCENT MOISTURE WINS.

WIN Y%=PERCENT YIELD WINS.

YLD=YIELD. It is the same as BU ACR ABS.

YLD ADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety #2 as calculated by: YIELD of variety #1 - YIELD variety #2=yield advantage of variety #1.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.

DETAILED DESCRIPTION OF THE INVENTION

Inbred maize lines are typically developed for use in the production of hybrid maize lines. Inbred maize lines need to be highly homogeneous, homozygous and reproducible to be useful as parents of commercial hybrids. There are many analytical methods available to determine the homozygotic and phenotypic stability of these inbred lines.

The oldest and most traditional method of analysis is the observation of phenotypic traits. The data is usually collected in field experiments over the life of the maize plants to be examined. Phenotypic characteristics most often observed are for traits associated with plant morphology, ear and kernel morphology, insect and disease resistance, maturity, and yield.

In addition to phenotypic observations, the genotype of a plant can also be examined. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), and Simple Sequence Repeats (SSRs) which are also referred to as Microsatellites.

The most widely used of these laboratory techniques are Isozyme Electrophoresis and RFLPs as discussed in Lee, M., "Inbred Lines of Maize and Their Molecular Markers," The Maize Handbook, (Springer-Verlag, New York, Inc. 1994, at 423-432) incorporated herein by reference. Isozyme Electrophoresis is a useful tool in determining genetic composition, although it has relatively low number of available markers and the low number of allelic variants among maize inbreds. RFLPs have the advantage of revealing an exceptionally high degree of allelic variation in maize and the number of available markers is almost limitless.

Maize RFLP linkage maps have been rapidly constructed and widely implemented in genetic studies. One such study is described in Boppenmaier, et al., "Comparisons among strains of inbreds for RFLPs", Maize Genetics Cooperative Newsletter, 65:1991, pg. 90, is incorporated herein by reference. This study used 101 RFLP markers to analyze the patterns of 2 to 3 different deposits each of five different inbred lines. The inbred lines had been selfed from 9 to 12 times before being adopted into 2 to 3 different breeding programs. It was results from these 2 to 3 different breeding programs that supplied the different deposits for analysis. These five lines were maintained in the separate breeding programs by selfing or sibbing and rogueing off-type plants for an additional one to eight generations. After the RFLP analysis was completed, it was determined the five lines showed 0-2% residual heterozygosity. Although this was a relatively small study, it can be seen using RFLPs that the lines had been highly homozygous prior to the separate strain maintenance.

PHAG6 has very good per se yield and yields very well in hybrid combination. PHAG6 has very good brittle stalk resistance.

Inbred maize line PHAG6 is a yellow, dent maize inbred that provides an acceptable female parental line in crosses for producing first generation F1 maize hybrids. PHAG6 is adapted to most regions of the United States.

The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Description Information (Table 1) that follows. Most of the data in the Variety Description information was collected at Johnston, Ia. The inbred has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to ensure the homozygousity and phenotypic stability necessary to use in commercial production. The line has been increased both by hand and in isolated fields with continued observation for uniformity. No variant traits have been observed or are expected in PHAG6. Inbred maize line PHAG6, being substantially homozygous, can be reproduced by planting seeds of the line, growing the resulting maize plants under self-pollinating or sib-pollinating conditions with adequate isolation, and harvesting the resulting seed, using techniques familiar to the agricultural arts.

                  TABLE 1                                                          ______________________________________                                         VARIETY DESCRIPTION INFORMATION                                                INBRED = PHAG6                                                                 ______________________________________                                             Type: Dent      Region Best Adapted: North Central                         A.  Maturity: Average across maturity zones. Zone : 0                              GDU Shed: 1460                                                                 GDU Silk: 1490                                                                 No. Reps: 46                                                               B.  Plant Characteristics:                                                         Plant height (to tassel tip): 212 cm                                           Length of top ear internode: 13 cm                                             Number of ears per stalk: Slight, two ear tendency                             Ear height (to base to top ear): 74 cm                                         Number of tillers: None                                                        Cytoplasm type: Normal                                                     C.  Leaf:                                                                          Color: (B14) Dark Green*                                                       Angle from Stalk: <30 degrees                                                  Marginal Waves: (WF9) Few                                                      Number of Leaves (mature plants): 21                                           Sheath Pubescence: (W22) Light                                                 Longitudinal Creases: (PA11) Many                                              Length (Ear node leaf): 81 cm                                                  Width (widest point, ear node leaf): 9 cm                                  D.  Tassel:                                                                        Number of branches: 2                                                          Branch angle from central spike: 30-40 degrees                                 Pollen Shed: (WF9) Light based on Pollen Yield Test                            (32% of experiment means)                                                      Peduncle Length (top leaf to basal branches): 21 cm                            Anther Color: Red*                                                             Glume Color: Green*                                                        E.  Ear (Husked Ear Data Except When Stated Otherwise):                            Length: 14 cm                                                                  Weight: 108 gm                                                                 Mid-point Diameter: 42 mm                                                      Silk Color: Salmon*                                                            Husk Extension (Harvest stage): Medium (barely covering                        ear)                                                                           Husk Leaf: Short (<8 cm)                                                       Taper of Ear: Average                                                          Position of Shank (dry husks): Horizontal                                      Kernel Rows: Straight, distinct Number = 18                                    Husk Color (fresh): Light Green*                                               Husk Color (dry): Buff*                                                        Shank Length: 11 cm                                                            Shank (No. of internodes): 7                                               F.  Kernel (Dried):                                                                Size (from ear mid-point)                                                      Length: 10 mm                                                                  Width: 7 mm                                                                    Thick: 5 mm                                                                    Shape Grade (% rounds): 20-40 (25% medium round                                based on                                                                       Parent Test Data)                                                              Pericarp Color: Colorless*                                                     Aleurone Color: Homozygous Yellow*                                             Endosperm Color: Yellow*                                                       Endosperm Type: Normal Starch                                                  Gm Wt/100 Seeds (unsized): 22 gm                                           G.  Cob:                                                                           Diameter at mid-point: 27 mm                                                   Strength: Strong                                                               Color: Red*                                                                H.  Diseases:                                                                      Corn Lethal Necrosis (MCMV = Maize Chlorotic Mottle                            Virus and                                                                      MDMV = Maize Dwarf Mosaic  Virus): Intermediate                                Maize Dwarf Mosaic Complex (MDMV & MCDV =                                      Maize Dwarf                                                                    Virus): Susceptible                                                            Anthracnose Stalk Rot (C. graminicola): Susceptible                            N. Leaf Blight (E. turcicum): Susceptible                                      Common Rust (P. sorghi): Intermediate                                          Southern Rust (P. polysora): Intermediate                                      Gray Leaf Spot (C. zeae): Susceptible                                          Stewart's Wilt (E. stewartii): Intermediate                                    Head Smut (S. reiliana): Susceptible                                           Fusarium Ear Mold (F. moniliforme): Intermediate                           I.  Insects:                                                                       European Corn Borer-1 Leaf Damage (Pre-flowering):                             Susceptible                                                                    European Corn Borer-2 (Post-flowering): Susceptible                            The above descriptions are based on a scale of 1-9, 1 being                    highly susceptible, 9 being highly resistant.                                  S (Susceptible): Would generally represent a score of 1-3.                     I (Intermediate): Would generally represent a score of 4-5.                    R (Resistant): Would generally represent a score of 6-7.                       H (Highly Resistant): Would generally represent a score                        of 8-9.                                                                        Highly resistant does not imply the inbred is                                  Immune.                                                                    J.  Variety Most Closely Resembling:                                               Character  Inbred                                                              Maturity   PHHB9                                                               Usage PHHB9                                                                ______________________________________                                          *In interpreting the foregoing color designations, reference may be had t      the Munsell Glossy Book of Color, a standard color reference.                  Data for Items B, C, D, E, F, and G is based primarily on a maximum of         four reps from Johnston, Iowa grown in 1993 and 1994, plus description         information from the maintaining station.                                      PHHB9 (PVP Certificate No. 9300108) is a Pioneer HiBred International,         Inc. propriety inbred.                                                   

ELECTROPHORESIS RESULTS Isozyme Genotypes for PHAG6

Isozyme data were generated for inbred maize line PHAG6 according to the procedures described in Stuber, C. W., Wendie, J. F., Goodman, M. M., and Smith, J. S. C., "Techniques and Scoring Procedures for Starch Gel Electrophoresis of Enzymes from Maize (Zea mays L.)," Technical Bulletin No. 286, North Carolina Agricultural Research Service, North Carolina State University, Raleigh, N.C. (1988).

The data in Table 2 compares PHAG6 with its parents, PH323 and PHP38.

                  TABLE 2                                                          ______________________________________                                         ELECTROPHORESIS RESULTS FOR PHAG6                                              AND ITS PARENTS PH323 AND PHP38                                                                  PARENTS                                                      LOCI     PHAG9          PH323   PHP38                                          ______________________________________                                         ACP1     2              2       4                                              ADH1     4              4       4                                              CAT3     9              9       9                                              DIA1     8              8       8                                              GOT1     4              4       4                                              GOT2     4              4       2                                              GOT3     4              4       4                                              IDH1     4              4       4                                              IDH2     6              4       6                                              MDH1     6              6       6                                              MDH2     6              3.5     6                                              MDH3     16             16      16                                             MDH4     12             12      12                                             MDH5     12             12      12                                             MMM      4              4       4                                              PGM1     9              9       9                                              PGM2     4              4       4                                              PGD1     2              3.8     2                                              PGD2     5              5       5                                              PHI1     4              4       4                                              ______________________________________                                    

Industrial Applicability

This invention also is directed to methods for producing a maize plant by crossing a first parent maize plant with a second parent maize plant wherein the first or second parent maize plant is an inbred maize plant from the line PHAG6. Further, both first and second parent maize plants can come from the inbred maize line PHAG6. Thus, any such methods using the inbred maize line PHAG6 are part of this invention: selfing, backcrosses, hybrid production, crosses to populations, and the like. All plants produced using inbred maize line PHAG6 as a parent are within the scope of this invention. Advantageously, the inbred maize line is used in crosses with other, different, maize inbreds to produce first generation (F₁) maize hybrid seeds and plants with superior characteristics.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which maize plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like.

Duncan, Williams, Zehr, and Widholm, Planta (1985) 165:322-332 reflects that 97% of the plants cultured that produced callus were capable of plant regeneration. Subsequent experiments with both inbreds and hybrids produced 91% regenerable callus that produced plants. In a further study in 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988), 7:262-265 reports several media additions that enhance regenerability of callus of two inbred lines. Other published reports also indicated that "nontraditional" tissues are capable of producing somatic embryogenesis and plant regeneration. K. P. Rao, et al., Maize Genetics Cooperation Newsletter, 60:64-65 (1986), refers to somatic embryogenesis from glume callus cultures and B. V. Conger, et al., Plant Cell Reports, 6:345-347 (1987)indicates somatic embryogenesis from the tissue cultures of maize leaf segments. Thus, it is clear from the literature that the state of the art is such that these methods of obtaining plants are, and were, "conventional" in the sense that they are routinely used and have a very high rate of success.

Tissue culture of maize is described in European Patent Application, publication 160,390, incorporated herein by reference. Maize tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize," Maize for Biological Research (Plant Molecular Biology Association, Charlottesville, Va. 1982, at 367-372) and in Duncan, et al., "The Production of Callus Capable of Plant Regeneration from Immature Embryos of Numerous Zea Mays Genotypes," 165 Planta 322-332 (1985). Thus, another aspect of this invention is to provide cells that upon growth and differentiation produce maize plants having the physiological and morphological characteristics of inbred line PHAG6.

Maize is used as human food, livestock feed, and as raw material in industry. The food uses of maize, in addition to human consumption of maize kernels, include both products of dry- and wet-milling industries. The principal products of maize dry milling are grits, meal and flour. The maize wet-milling industry can provide maize starch, maize syrups, and dextrose for food use. Maize oil is recovered from maize germ, that is a by-product of both dry- and wet-milling industries.

Maize, including both grain and non-grain portions of the plant, is also used extensively as livestock feed, primarily for beef cattle, dairy cattle, hogs, and poultry.

Industrial uses of maize include production of ethanol, maize starch in the wet-milling industry and maize flour in the dry-milling industry. The industrial applications of maize starch and flour are based on functional properties, such as viscosity, film formation, adhesive properties, and ability to suspend particles. The maize starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, and other mining applications.

Plant parts other than the grain of maize are also used in industry: for example, stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.

The seed of inbred maize line PHAG6, the plant produced from the inbred seed, the hybrid maize plant produced from the crossing of the inbred, hybrid seed, and various parts of the hybrid maize plant can be utilized for human food, livestock feed, and as a raw material in industry.

Performance Examples of PHAG6

In the examples that follow, the traits and characteristics of inbred maize line PHAG6 are given as a line in comparison with other inbreds. The data collected on inbred maize line PHAG6 is presented for the key characteristics and traits.

Table 3A compares PHAG6 to its PH323 parent. Compared to PH323, PHAG6 has slightly better yield, though not significant, and lower grain harvest moisture. PHAG6 has better staygreen, higher test weight and better grain appearance than PH323. PHAG6 is shorter with lower ear placement compared to PH323.

The data in Table 3B compares PHAG6 to its PHP38 parent. PHAG6 has higher yield and lower grain harvest moisture than PHP38. PHAG6 is a shorter inbred with similar ear height compared to PHP38.

The data in Table 3C shows PHAG6 has lower yield and grain harvest moisture than PHT47 PHAG6 is shorter with lower ear placement and sheds (GDU shed) earlier than PHT47.

Table 3D compares PHAG6 to PHT11. PHAG6 has significantly higher yield and grain harvest moisture compared to PHT11. PHAG6 has better root lodging resistance and staygreen than PHT11. PHAG6 has significantly better brittle stalk resistance than PHT11.

The data in Table 3E, comparing PHAG6 and PHHB9, shows PHAG6 has lower yield and grain harvest moisture than PHHB9. PHAG6 is a shorter inbred with higher ear placement and has significantly better brittle stalk resistance than PHHB9.

Table 4 compares the general combining ability of PHAG6 to that of PHP38. The results show a similar yield and maturity. PHAG6 has a slightly lower moisture at harvest.

Table 5 contains data from a paired hybrid comparison of a PHAG6 hybrid and a PHHB9 hybrid. The PHAG6 hybrid demonstrates a higher yield, a lower moisture at harvest, a higher test weight and an earlier GDU to shed than the PHHB9 hybrid.

                                      TABLE 3A                                     __________________________________________________________________________     PAIRED INBRED COMPARISON DATA                                                  VARIETY #1 = PHAG6                                                             VARIETY #2 = PH323                                                             __________________________________________________________________________                          BU  BU       STK  RT  STA  TST                                    VAR      PRM ACR ACR MST  LDG  LDG GRN  WTA                                    #   PRM  SHD ABS % MN                                                                               % MN % MN % MN                                                                               % MN % MN                           __________________________________________________________________________     TOTAL SUM                                                                              1   111  110 76.1                                                                               113 96   91   104 103  102                                    2   115  112 73.8                                                                               107 108  101  99  77   97                                     LOCS                                                                               1    4   17  17  24   11   3   20   15                                     REPS                                                                               1    4   31  31  38   20   4   30   26                                     DIFF                                                                               4    2   2.3 5   12   10   5   25   5                                      PROB     .275                                                                               .665                                                                               .500                                                                               .000#                                                                               .066*                                                                               .423                                                                               .032+                                                                               .011+                          __________________________________________________________________________                 GRN  SDG EST STK PLT  EAR  BRT GDU                                         VAR APP  VGR CNT CNT HT   HT   STK SHD                                         #   % MN % MN                                                                               % MN                                                                               % MN                                                                               % MN % MN % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                              1   98   106 99  99  95   99   108 100                                         2   77   100 103 100 109  123  103 101                                         LOCS                                                                               9    35  59  71  25   24   10  34                                          REPS                                                                               17   53  118 99  39   37   13  39                                          DIFF                                                                               21   5   4   2   14   24   5   1                                           PROB                                                                               .023+                                                                               .251                                                                               .298                                                                               .438                                                                               .000#                                                                               .000#                                                                               .257                                                                               .001#                               __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

                                      TABLE 3B                                     __________________________________________________________________________     PAIRED INBRED COMPARISON DATA                                                  VARIETY #1 = PHAG6                                                             VARIETY #2 = PHP38                                                             __________________________________________________________________________                      PRM  BU   BU        STK  RT   STA  TST                                VAR      SHD  ACR  ACR  MST  LDG  LDG  GRN  WTA                                #   PRM  ABS  % MN % MN % MN % MN % MN % MN % MN                       __________________________________________________________________________     TOTAL SUM                                                                              1   110  110  78.9 119  98   90   104  100  102                                2   112  110  72.1 106  104  104  104  130  103                                LOCS                                                                               3    7    35   35   46   19   16   38   29                                 REPS                                                                               3    7    67   67   79   37   25   58   55                                 DIFF                                                                               2    0    6.8  12   6    14   0    31   1                                  PROB                                                                               .138 .955 .003#                                                                               .004#                                                                               .000#                                                                               .013+                                                                               .860 .000#                                                                               .041+                      __________________________________________________________________________                 GRN  SDG  EST  STK  PLT  EAR  DRP  BRT  GDU                                VAR APP  VGR  CNT  CNT  HT   HT   EAR  STK  SHD                                #   % MN % MN % MN % MN % MN % MN % MN % MN % MN                       __________________________________________________________________________     TOTAL SUM                                                                              1   102  102  99   99   95   99   100  103  101                                2   114  116  103  102  98   96   100  102  100                                LOCS                                                                               13   83   126  132  54   53   5    26   77                                 REPS                                                                               25   113  204  182  83   81   10   32   85                                 DIFF                                                                               12   14   4    2    3    3    0    1    0                                  PROB                                                                               .073*                                                                               .000#                                                                               .042+                                                                               .049+                                                                               .000#                                                                               .118 .703 .480 .711                       __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

                                      TABLE 3C                                     __________________________________________________________________________     PAIRED INBRED COMPARISON DATA                                                  VARIETY #1 = PHAG6                                                             VARIETY #2 = PHT47                                                             __________________________________________________________________________                      BU   BU        STK  RT  STA  TST  GRN                                 VAR PRM  ACR  ACR  MST  LDG  LDG GRN  WTA  APP                                 #   SHD  ABS  % MN % MN % MN % MN                                                                               % MN % MN % MN                        __________________________________________________________________________     TOTAL SUM                                                                              1   110  70.7 124  105  93   107 111  102  99                                  2   110  78.7 138  112  105  109 148  103  117                                 LOCS                                                                               3    9    9    11   6    5   19   8    4                                   REPS                                                                               3    18   18   22   12   8   25   16   7                                   DIFF                                                                               0    8.0  15   7    12   2   37   1    18                                  PROB                                                                               .943 .020+                                                                               .031+                                                                               .003#                                                                               .108 .240                                                                               .001#                                                                               .042+                                                                               .153                        __________________________________________________________________________                 SDG  EST  STK  PLT  EAR  DRP BRT  GDU                                      VAR VGR  CNT  CNT  HT   HT   EAR STK  SHD                                      #   % MN % MN % MN % MN % MN % MN                                                                               % MN % MN                             __________________________________________________________________________     TOTAL SUM                                                                              1   103  100  106  94   99   100 103  101                                      2   121  102  102  111  103  99  103  102                                      LOCS                                                                               31   48   43   24   24   3   16   42                                       REPS                                                                               35   94   59   31   31   6   19   47                                       DIFF                                                                               17   2    3    17   4    1   0    1                                        PROB                                                                               .001#                                                                               .486 .094*                                                                               .000#                                                                               .032+                                                                               .700                                                                               .627 .015+                            __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

                                      TABLE 3D                                     __________________________________________________________________________     PAIRED INBRED COMPARISON DATA                                                  VARIETY #1 = PHAG6                                                             VARIETY #2 = PHT11                                                             __________________________________________________________________________                      BU   BU        STK  RT  STA   TST  GRN                                VAR PRM  ACR  ACR  MST  LDG  LDG GRN   WTA  APP                                #   SHD  ABS  % MN % MN % MN % MN                                                                               % MN  % MN % MN                       __________________________________________________________________________     TOTAL SUM                                                                              1   110  71.3 125  103  93   106 109   102  99                                 2   109  40.6 69   90   91   87  76    103  107                                LOCS                                                                               5    10   10   16   6    9   17    8    4                                  REPS                                                                               5    20   20   27   11   12  23    16   7                                  DIFF                                                                               1    30.7 57   14   2    19  33    1    8                                  PROB                                                                               .364 .000#                                                                               .000#                                                                               .009#                                                                               .758 .024+                                                                              .001# .268 .668                       __________________________________________________________________________                 SDG  EST  STK  PLT  EAR  DRP BRT   GDU                                     VAR VGR  CNT  CNT  HT   HT   EAR STK   SHD                                     #   % MN % MN % MN % MN % MN % MN                                                                               % MN  % MN                            __________________________________________________________________________     TOTAL SUM                                                                              1   99   99   100  95   100  100 105   101                                     2   113  103  102  114  110  100 95    100                                     LOCS                                                                               47   82   80   28   27   3   17    60                                      REPS                                                                               58   137  101  39   37   6   21    65                                      DIFF                                                                               14   4    2    19   10   1   11    1                                       PROB                                                                               .003#                                                                               .052*                                                                               .216 .000#                                                                               .001#                                                                               .423                                                                               .039+ .002#                           __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

                                      TABLE 3E                                     __________________________________________________________________________     PAIRED INBRED COMPARISON DATA                                                  VARIETY #1 = PHAG6                                                             VARIETY #2 = PHHB9                                                             __________________________________________________________________________                         BU   BU        STK  RT   STA  TST                                  VAR     PRM ACR  ACR  MST  LDG  LSG  GRN  WTA                                  #   PRM SHD ABS  % MN % MN % MN % MN % MN % MN                         __________________________________________________________________________     TOTAL SUM                                                                              1   110 110 89.1 118  94   86   105  95   102                                  2   115 111 97.3 127  105  103  102  129  102                                  LOCS                                                                               2   7   14   14   27   10   8    25   14                                   REPS                                                                               2   7   25   25   42   20   10   32   27                                   DIFF                                                                               5   1   8.2  9    11   17   3    33   0                                    PROB                                                                               .177                                                                               .106                                                                               .196 .299 .000#                                                                               .081*                                                                               .351 .000#                                                                               .967                         __________________________________________________________________________                 GRN SDG EST  STK  PLT  EAR  BRT  GDU                                       VAR APP VGR CNT  CNT  HT   HT   STK  SHD                                       #   % MN                                                                               % MN                                                                               % MN % MN % MN % MN % MN % MN                              __________________________________________________________________________     TOTAL SUM                                                                              1   101 103 100  100  94   98   103  101                                       2   103 102 107  104  102  90   98   101                                       LOCS                                                                               12  57  87   97   40   40   20   71                                        REPS                                                                               23  65  135  117  54   54   20   78                                        DIFF                                                                               2   1   7    5    8    8    5    0                                         PROB                                                                               .838                                                                               .847                                                                               .008#                                                                               .010+                                                                               .000#                                                                               .001#                                                                               .051*                                                                               .288                              __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

                                      TABLE 4                                      __________________________________________________________________________     Average Inbred By Tester Performance Comparing PHAG6 To                        PHP38 Crossed To The Same Inbred Testers And Grown In The Same                 Experiments. All Values Are Expressed As Percent Of The Experiment             Mean Except Predicted RM, Selection Index, and Yield (BU/ACR)                  __________________________________________________________________________                      SEL BU          GDU PRM                                              INBRED                                                                               PRM IND ACR YLD MST SHD SHD                                       __________________________________________________________________________     TOTAL  REPLIC.                                                                              103 88  102 102 103 31  18                                        MEAN WTS                                                                              PHAG6 111 101 162 101 98  100 112                                       MEAN WTS                                                                              PHP38 112 102 162 101 100 100 112                                              DIFF  1   2   1   1   2   0   0                                         __________________________________________________________________________                  STK RT  STA TST GRN SDG                                                  INBRED                                                                               LDG LDG GRN WTA APP VGR                                           __________________________________________________________________________     TOTAL  REPLIC.                                                                              87  30  55  88  65  42                                            MEAN WTS                                                                              PHAG6 98  99  97  100 100 87                                            MEAN WTS                                                                              PHP38 102 97  123 101 111 98                                                   DIFF  4   2   26  1   12  11                                            __________________________________________________________________________                  EST STK PLT EAR DRP BRT                                                  INBRED                                                                               CNT CNT HT  HT  EAR STK                                           __________________________________________________________________________     TOTAL  REPLIC.                                                                              75  117 58  58  53  9                                             MEAN WTS                                                                              PHAG6 99  99  99  101 100 102                                           MEAN WTS                                                                              PHP38 97  98  99  100 100 101                                                  DIFF  2   1   0   1   0   1                                             __________________________________________________________________________

                                      TABLE 5                                      __________________________________________________________________________     VARIETY #1 = PHAG6 HYBRID                                                      VARIETY #2 = PHHB9 HYBRID                                                      __________________________________________________________________________                             BU   BU        TST  SDG  EST                                   VAR        PRM  ACR  ACR  MST  WT   VGR  CNT                                   #     PRM  SHD  ABS  % MN % MN ABS  % MN % MN                          __________________________________________________________________________     TOTAL SUM                                                                              1     117  115  198.2                                                                               111  110  59.4 89   100                                   2     118  116  191.2                                                                               106  113  58.8 94   99                                    LOCS  11   18   57   57   63   43   29   31                                    REPS  11   18   65   65   73   49   37   39                                    DIFF  1    2    7.0  5    3    0.7  5    0                                     PROB  .017+                                                                               .000#                                                                               .010+                                                                               .005#                                                                               .008#                                                                               .000#                                                                               .322 .857                          __________________________________________________________________________                   GDU  GDU  STK  PLT  EAR  RT   STA                                        VAR   SHD  SLK  CNT  HT   HT   LDG  GRN                                        #     % MN % MN % MN % MN % MN % MN % MN                               __________________________________________________________________________     TOTAL SUM                                                                              1     103  103  101  100  102  95   133                                        2     105  104  102  101  97   120  115                                        LOCS  20   17   70   30   30   22   31                                         REPS  24   18   87   37   37   25   40                                         DIFF  2    0    1    1    5    25   17                                         PROB  .000#                                                                               .349 .340 .110 .001#                                                                               .006#                                                                               .010+                              __________________________________________________________________________                   STK  BRT  GRN  DRP  GLF  MDM  ECB                                        VAR   LDG  STK  APP  EAR  SPT  CPX  DPE                                        #     % MN % MN % MN % MN ABS  ABS  ABS                                __________________________________________________________________________     TOTAL SUM                                                                              1     102  108  105  95   6.7  2.5  98.0                                       2     101  105  107  98   6.3  3.0  100.0                                      LOCS  41   10   5    9    3    1    1                                          REPS  48   14   5    12   3    2    1                                          DIFF  2    3    2    3    0.3  0.5  2.0                                        PROB  .167 .178 .715 .117 .423                                         __________________________________________________________________________      *= 10% SIG                                                                     += 5% SIG                                                                      #= 1% SIG                                                                

The foregoing invention has been described in detail by way of illustration and example for purposes of clarity and understanding. However, it will be obvious that certain changes and modifications such as single gene modifications and mutations, somoclonal variants, variant individuals selected from large populations of the plants of the instant inbred and the like may be practiced within the scope of the invention, as limited only by the scope of the appended claims. 

What is claimed is:
 1. Seed of maize inbred line designated PHAP6 and having ATCC Accession No.
 97575. 2. A maize plant produced by the seed of claim 1 and its plant parts.
 3. Pollen of the plant of claim
 2. 4. An ovule of the plant of claim
 2. 5. A maize plant having all the physiological and morphological characteristics of the maize plant named PHAG6, the seed of which have been deposited under ATCC Accession No.
 97575. 6. A male sterile maize plant otherwise having all the physiological and morphological characteristics of the maize plant named PHAG6, the seed of which have been deposited under ATCC Accession No.
 97575. 7. A tissue culture of regenerable cells of an inbred maize plant PHAG6, wherein the tissue regenerates plants capable of expressing all the morphological and physiological characteristics of the maize plant named PHAG6, the seed of which have been deposited under ATCC Accession No.
 97575. 8. A tissue culture of claim 7, the tissue culture selected from the group consisting of leaves, pollen, embryos, roots, root tips, anthers, silk, flowers, kernels, ears, cobs, husks, stalks, cells and protoplasts thereof.
 9. A maize plant regenerated from the tissue culture of claim 7, capable of expressing all the morphological and physiological characteristics of inbred PHAG6, the seed of which have been deposited under ATCC Accession No.
 97575. 10. A method for producing first generation (F₁) hybrid maize seed comprising crossing a first inbred parent maize plant with a second inbred parent maize plant and harvesting the resultant first generation (F₁) hybrid maize seed, wherein said first or second parent maize plant is the maize plant of claim
 2. 11. The method of claim 10 wherein inbred maize plant PHAG6, the seed of which have been deposited under ATCC Accession No. 97575, is the female parent.
 12. The method of claim 10 wherein inbred maize plant PHAG6, the seed of which have been deposited under ATCC Accession No. 97575, is the male parent.
 13. An F₁ hybrid seed and plant grown therefrom, and its parts, produced by crossing an inbred maize plant according to claim 2 with another, different maize plant. 